Vacuum casting-machine.



L. R. CURTIS.

VACUUM CASTING MACHINE.

APPLICATION FILED MAY 2, 1911.

Patented Apr. 15,1919.

TNT

LOUIS R. CURTIS, OF CHICAGO, ILLINOIS, ASSIGNOR TO FRANK S. BETZ COMPANY, OF

HAMMOND, INDIANA, A CORPORATION OF INDIANA.

vacuum CASTING-MACHINE.

ing machine-adapted for use by'dentists to shape gold inlays and the like; to provide a casting machine with a spring-operated piston for creating a vacuum; and to provide a casting machine having a pump adapted to be set or locked under spring pressure,'and actuated by merely releasing a detent to exhaust the air from the casting cup. a

An illustrative embodiment of this invenfi tion-is shown'in the accompanying drawings, in whichv Figure 1 is a vertical longitudinal sectional elevation of the improved casting machine, the position of the operating parts when in set position being shown in dotted outline. l i i r Fig. 2 is a front endelevation, partly in section, taken on the line A-A of Fig.1.

This invention relates to vacuum casting machines used in dentistry work for making gold inlays and the like, and possesses theadvantage of being spring-operated and arranged so that the device may be set or locked with the spring in. compressed position,and when it is desired, it may be readily unlocked or released, thus permitting the spring to shift the pistonin the vacuum pump and thereby create the vacuum. V y

In the construction shown in the draw.-

ings, a casting cup 1 of the usual construe-j tion is mounted frictionally in a coupling 2 which is threaded on the upper end of an upstanding pipe 3. The pipe 3 is mounted at its lower end on, and communicates with, a vacuum pump 4.1

The vacuum pump comprises a cylinder 5 having a stop member 6 rigidly mounted therein medially of its ends, and the end of the cylinder opposite that which communicates with the casting cup is closed by a cap 7 threaded thereon. A piston 8 is slidably mounted in the cylinder 5 between the stop member 6 and the end of the cylinder Patented Apr. 15, 1919.

Application filed May 2, 1917. Serial No. 165,842..

n position to bear between the stop member 6 of the cylinder and the stop member 10 of the piston rod, thus normally urging the piston 8 away from the end of the cylinder 5 which communicates with the casting cup 1.

A lever 12 is pivoted medially of its ends at 13 to the outer end of the piston rod 9, and a link 14, one end of which is pivoted at 15 toone end of the lever 12 and the other end of which is pivoted at 16 to an upstanding post 17 on the cylinder cap 7, connects the lever to the cylinder. The other end 18 of'the lever-12 is shaped and adapted to serve, as a handle, and the arrangement of said handle and connecting link is such that when the handle is moved to the position shown in dotted lines in Fig. 1, the piston rod is forced inwardly, thereby carrying the piston. S'adjacent to the end of the cylinder 5 which communicates with the casting cup 1, as shown in dotted lines in Fig. 1, thus compressing the compression spring between the stop members 6 and 10. 1 The piston rod 9 is provided with an annular groove or notch 19 located in such position that when the piston rod is forced inwardly, as shown in dotted outline in Fig. l, the annular groove will be adjacent the outer side of the cylinder cap 7, and in position to coact with a locking member or detent 20 pivoted at 21 on the cylinder cap 7 and which is normally urged against the piston rod 9 by suitable yielding means, such as coiled spring 22. The outer end 23 of the detent 20 is shaped so as to provide a suitable bearing surface, so that the operator can press downward thereon and thereby disengage the; detent from the notch 19. The downward movement of the detent 20 is limited by a pin 24 mounted on cap 7.

The entire device is mounted on the top of a work-bench 25, or other convenient place, by means of depending supporting legs 26, the feet of which have apertures therein for receiving screws 27 In the operation of the device, the handle 18 is grasped by the operator and forced inwardly to the position shown in dotted outline in Fig. 1, until the annular groove 19 comes into position so as to coact with the detent 20. When in this position the piston 8 is adjacent the end of the pumping cylinder 5 which communicates with the casting cup 1. The plaster of Paris mold is then prepared in the casting cup in the usual manner, and the gold or other substance to be cast is heated as is customarily done, and when the metal to be cast has been melted, and is in condition to be drawn into the mold, the operator presses down on the hearing surface 23 of the detent 20, thereby disengaging the detent from the groove or notch 19 in the piston rod 9. Immediately upon unlocking the piston rod the coiled compression spring 11 rapidly draws the piston 8 away from the end of the cylinder 5,

which communicates with the casting cup, thereby tending to exhaust the air from the pipe 3, coupling 2, and casting cup 1, thus drawing the molten metal down into the mold.

This construction and arrangement has many advantages over the ordinary type of casting machine, in which the piston is manually drawn out when it is desired to create the vacuum. By the use of the compression spring for shifting the piston 8, the device may be set, and then when the metal is in condition to be cast the piston may be readily unlocked quickly and with very little effort, and the compression spring 11 draws the piston out much more rapidly than could be done by an operator.

Although but one specific embodiment of this invention has been herein shown and described, it will be understood that numerous details of the construction shown may be altered or omitted without departing from the spirit of this invention as defined by the following claims.

I claim v 1. In a casting machine, a vacuum pump comprising in combination a cylinder, a suction pipe communicating with one end of said cylinder, a stop member mounted in said cylinder medially of the ends thereof, a piston slidably mounted in said cylinder between said stop member and the said one end of the cylinder, a piston rod mounted on the side of said piston adjacent to said stop member, a second stop member mounted on said piston rod, a compression spring mounted between said stop members, said spring being arranged and adapted to normally urge said piston away from the said one end Copies, of this patent may be obtained for of said cylinder, a detent pivoted on the opposite end of said cylinder and movable in a plane extending transversely of the cylinder axis, and yielding means arranged and adapted to urge said detent against said piston rod, said piston rod being provided with a notch therein for receiving said detent, said notch being located in position to co'act automatically with said detent for locking said rod when said piston is adjacent to the said one end of the cylinder, said detent being manually retractable from said notch to release said rod and so permit said compression spring to shift said piston away from said one end and the suction pipe communicating therewith.

2. A quick acting suction pump, comprising in combination a piston chamber and piston therefor having a rod connected operatively thereto, said chamber at one end being provided with a. suction conduit and at its other end being provided with a guide for the piston rod, yielding means adapted to urge said piston from said conduit, said rod having a lateral aperture and said guide having a detent mounted operatively thereon for engagement with said aperture, resilient means for urging said detent into such engagement, and said detent being releasable manually whenever suction is deslred in said conduit, said aperture and detent being disposed relatively to each other for mutual engagement when the piston is near said conduit. I r

3. A quick acting suction pump, comprising in combination a tubular bod having walls at each end and a medial wa 1, one of the end walls having a suction conduit connected thereto, the other two walls being apertured in alinement to serve as guides, a piston rod operably mounted in the guide apertures, a piston on said rod adapted to produce a vacuum in the'suction conduit end of the body when the rod is moved outward therefrom, and a detent lever pivoted on an Louis B. cun ris;

five cents each, by addressing the Commissioner of Patents, Washington, D. G. a 

